Most lubricants and functional fluids are easily contaminated with water. Accordingly water compatibility is a highly significant property of functional fluids and lubricants. The significance of this property is most important under severe conditions such as when functional fluids and lubricants come into contact with water under extreme pressure and temperature conditions.
In the absence of acceptable water tolerance properties, such functional fluids and lubricants will have its lubricating and/or power transmission properties substantially reduced. Fluid flow is not smooth when water separates out and the separated water can be vaporized to steam at high temperature. Accordingly, many manufacturers of equipment requiring the use of functional fluids and lubricants require that such fluids and lubricants process specific water tolerance properties. For example, manufacturers of agricultural tractor machinery have specific requirements with respect to the tractor fluids used in connection with the machinery; and, such requirements include specific water tolerance properties which the manufacturer believes to be necessary for the equipment to operate successfully under severe conditions.
In addition, a fluid with poor water tolerance properties becomes turbid and the clarity of functional fluids often impacts greatly on the fluid's marketability. A fluid that is turbid or becomes turbid after a short period of use is often unacceptable to consumers regardless of the performance characteristics of the fluid. Improved clarity not only increases marketability but allows the user to more readily and accurately determine when the fluid should be replaced.
U.S. Pat. No. 4,579,672 discloses functional fluids and lubricants having improved water tolerance properties. The compositions are comprised of major amounts of a synthetic or mineral oils of lubricating viscosity with minor amounts of oil soluble alkoxypolyethyleneoxy acid phosphite ester compounds dispersed therein as the water tolerance improving compounds.
U.S. Pat. No. 3,791,971 discloses polyoxyalkylene glycols and their reaction products with organic diisocyanate and dicarboxylic acid. These reaction products are combined with alkaline earth metal carbonates and dispersed in a hydrocarbon medium to provide lubricating compositions which are indicated as having superior acid neutralization capability and rust inhibiting properties when used within internal combustion engines. A number of compounds are disclosed throughout the 3,791,971 patent such as those encompassed by the general structural formulation shown at column 2, lines 44-55.
U.S. Pat. No. 4,265,774 discloses high molecular weight polygylcerol derivatives which are indicated as being useful as thickening agents for water-based lubricants. A large number of compounds encompassed by the general structural formula as shown at column 1, lines 35-45 are disclosed.
U.S. Pat. No. 3,625,893 discloses lubricating oil compositions which include minor amounts of basic group II metals salts of carboxylic acids and napthenic acids. The oil compositions including the additives are indicated as having improved oxidation stability and antirust properties.
U.S. Pat. No. 4,088,590 discloses brake fluids and operating fluids for central hydraulic installations in motor vehicles which are indicated as having excellent temperature/viscosity behavior as well as good lubricating properties. The improved properties are indicated as being obtained by including additives in the form of polyethylene glycol alkyl ether-based fluids of alkyl polyethylene glycol-t-butyl ethers. Amounts of the additive and a structural formula encompassing the additive is shown within the 4,088,590 patent at column 1, lines 7-19.
The present inventors have discovered that improved functional fluids and lubricating compositions can be obtained by combining major amounts of an oil of lubricating viscosity with a minor amount of an additive component. In this respect, the present invention relates to the same general concept which is being carried out in the patents discussed above. However, the compounds which the present inventors utilize as the additive component is structurally different from and chemically distinct from the compounds referred to in the above-discussed patents. Although some of the compounds per se utilized by the present inventors to improve performance properties of compositions may not be completely novel compounds per se, such compounds as included within the oil compositions are novel compositions.
Sandoz Product Bulletin 7-200/85 refers to a number of surfactant compounds sold under the trademark Sandopan. These compounds generally conform to the formula: EQU R--O--(C.sub.n H.sub.2n O).sub.m R.sub.l COOX
where R is a fatty group containing 13 to 18 carbons, n is 2 to 4, m is 1 to 100, R.sub.1 is CH.sub.2 to C.sub.3 H.sub.6 and X is H or Na. These compounds are indicated as being useful in products such as cleaning fluids, cosmetics and toiletries.